#include <iostream>
#include <climits>
#include <numeric>
#include <cassert>
#include <algorithm>
#include <queue>
#include <map>
#include <stack>
#include <set>
#include <vector>
#include <array>
#include <memory>
#define IN(a,b) (a.find(b) != a.end())
#define p(a,b) make_pair(a,b)
#define readVec(a) for (int __i = 0; __i<(int)a.size();__i++){cin>>a[__i];}
// jimjam
template<typename T>
void pMin(T &a, T b) {if (b<a){a=b;}}
template<typename T>
void pMax(T &a, T b) {if (b>a){a=b;}}
template<typename T>
std::ostream& operator<<(std::ostream& os, const std::vector<T>& c);
template<typename A, typename B>
std::ostream& operator<<(std::ostream& os, const std::pair<A,B>& c) {std::cout << "(" << c.first << ", " << c.second << ")";return os;}
template<typename T>
std::ostream& operator<<(std::ostream& os, const std::vector<T>& c) {
if (c.size() == 0) {os << "{}"; return os;}
os << "{" << c[0];
for (int i = 1; i < (int)c.size(); i++) {os <<", "<<c[i];}
os << "}";
return os;
}
using namespace std;
int main() {
ios::sync_with_stdio(0);
cin.tie(0);
int n, k; cin >> n >> k;
vector<int> a(n);
vector<bool> included(n, true);
readVec(a);
priority_queue<pair<int,int>> pq;
for (int i = 1; i < n; i++) {
pq.push({a[i]-a[i-1], i});
}
for (int i = 0; i < k-1; i++) {
included[pq.top().second-1] = false;
pq.pop();
}
int ans=0,start=-1;
included.back()=false;
for (int i = 0; i < n; i++) {
if (start==-1) {
start=a[i];
}
if (!included[i]) {
ans += a[i]-start+1;
start=-1;
}
}
cout << ans << endl;
return 0;
}
